The present application is directed toward a system for detecting toner level in a cassette inserted into an image forming apparatus and, more specifically, to a system utilizing a sensed mass.
In known methods of print processing, toner particles mix with carrier beads included in a developer station. The mixture is then transferred to a surface portion of a photoreceptor drum. The toner particles are transferred from the drum surface to an image bearing substrate moving on a transfer belt. The toner particles are then fused onto the image bearing substrate.
It is desirable that the mixture includes predetermined, equal rations of carrier beads to toner particles. A disproportionate ration is indicative of a low level of toner in a cartridge contained in the cassette. If an image forming apparatus continues to operate on the low-level of toner, there increases a risk of damaging stations of the apparatus. For example, carrier beads may damage a surface of the sensitive photoreceptor drum. This damage may lead in a long term to image quality defects and more permanent mechanical problems.
A current technique practiced by many operators is a shake-up approach. In an attempt to reinsert the low-level toner cassette for continued operation, operators remove the cassette from a main body of the image forming apparatus, shake the cassette to distribute the remainder of toner volume, and reinsert the cassette for utilization in additional printing cycles. This technique may lead to a risk of damaging the stations as the machine stresses to operate on pulling a volume of air instead of a steady volume of toner. One method used to estimate a volume of toner in a cassette includes automatically tracking a number of media sheets output from the image bearing apparatus. One disadvantage associated with this technique is that the estimate is based off of average toner consumption for sheets. If the output requires additional toner to render images, the deviation is not considered. Accordingly, the indicated toner level may not match the actual volume.
There is no current system for distinguishing between full level and low level toner cassettes inserted in an image forming apparatus. It is desirable for a system to distinguish between new and used cassettes for extending a life of the apparatus.